The type of sweater a guy puts on when he's trying to impress the chick he's on a date with. It's the only nice piece of clothing he owns and you'll see him wearing it in pretty much every picture taken of him on a date.

Can also be a useful tool when you're trying to confirm if two people are dating.

Sally: "Jenny, I told Tony I just want to be friends, but he keeps wearing this nice sweater when he comes over, even if it's just to watch TV."